An Internet Protocol (IP) telephony system routes various types of communications, at least in part, via data packets that are communicated over a data network. The data network is commonly the Internet. The types of communications may be, for example, telephone calls, video calls, text and video messages, and other forms of telephony and data communications. The users of the Internet Protocol (IP) telephony system typically gain access to the Internet using an Internet service provider so that they can communicate via the IP telephony system.
Customers of an IP telephony system can place and receive telephone calls using various types of telephony devices. One type of telephony device is an IP telephone that is typically connected to an Internet service provider via a wired connection or router. Another type of telephony device is a soft-phone client running on a computer which can place and receive IP based telephone calls. Yet another type of telephony device is a mobile telephony device such as a mobile computing device, mobile phone or the like which has wireless transmission and reception capabilities, and is connected to a wireless router or to a base station of a cellular network, for example using WiFi or cellular telephone technology.
Another type of telephony device is an analog telephone which is connected to the Internet via terminal adaptor. The terminal adaptor converts analog signals from the telephone into data signals that pass over the Internet, and vice versa. In some embodiments multiple analog telephones may be coupled to the same terminal Analog telephone devices include, but are not limited to, standard telephones and document imaging devices such as facsimile machines. A configuration using a terminal adaptor is common where one or more analog telephones are located in a residence or business, and all of the telephones are connected to the same terminal adaptor. With this configuration, all of the analog telephones may share the same telephone number assigned to the terminal.
One example terminal adaptor is the HT503 FXS/FXO Port Analog Telephone Adaptor sold by Grandstream Networks, Inc., and described in a HT503 User Manual. The HT503 adaptor has an FXO port which is connected to the plain old telephone system (POTS), an FXS port which is connected to an analog telephone, and a WAN port which is connected to an IP telephony network through a data network such as the Internet. The HT503 adaptor allows the analog telephone to answer calls which are incoming from the IP telephony network and to place outbound calls using the IP telephony network. The HT503 adaptor also supports routing incoming calls received at the FXO port to the SIP network (IP telephony system) as part of out-of-box functionality. However, the HT503 adaptor does not support routing incoming calls received at the FXO port to both an IP telephony system and to an analog telephone for the same incoming call. Rather, the HT503 adaptor routes the incoming call to one or the other of the IP telephony system and the analog telephony, but not both.
A processor in the HT503 adaptor converts signaling and user traffic between the FXS port (which is connected to the analog telephone) and the WAN port (which is ultimately connected to the IP telephony system). In some instances certain outbound calls from the analog telephone may be directed by the processor to the POTS-connected FXO port, such as emergency calls or calls that are preceded by a special prefix or code which indicates that the calls are not to be handled by the IP telephony system.
In view of their digital, packetized operation, IP telephony systems may provide various services that enhance a customer's telephony experience and provide expanded or additional capabilities, particularly when dealing with inbound calls. But when using a prior art adaptor, an analog telephone connected to the prior art adapter is not able to participate in such enhanced or expanded services for a POTS-originated call.